week 10 Flashcards
Pelvic girdle
Hip bones ± sacrum
Orientating the Pelvis
ASIS and pubic tubercles line up in same coronal plane
* Inferior tip sacrum/base of coccyx lies just superior to pubic symphysis in transverse plane
* R & L ASIS line up in transverse plane
* Acetabulum is directed inferolaterally 4
Functions of the Pelvis
1) Support and protect pelvic viscera (organ)
2) Provides bony support for the birth canal/ an exist foe foetus
3) Provides extensive muscle attachment sites
4) Supports the weight of the head, trunk and upper limbs
5) Allows for weight transfer
* from trunk to lower limb
* Standing – weight to femurs
* Seated – weight to ischial tuberosities
what forms the pelvic inlet
Pubic crest
* Pectineal line
* Arcuate line
* Sacral alar & promontory
- False or greater pelvis
- Superior to pelvic inlet
what forms part of the pelvic outlet
- Apex of coccyx
- Ischial tuberosities
- Pubic symphysis (inferior edge)
- True or lesser pelvis
- Inferior to pelvic inlet
Pubic Symphysis – Secondary Cartilaginous Joint
Between the symphyseal surfaces of pubic bones
* Fibrocartilage disc
* Supported by ligaments
* Limited movement
* exception is in pregnancy
* the fibres soften
* Relaxin hormone
* Osteitis pubis
Sacroiliac Joint Classification
- Anteriorly
- Synovial
- Plane joint
- Non-axial
- Posteriorly
- Fibrous joint
- Due to massive interosseus ligaments
articular surfaces of sacroiliac joint
auricular surface of the ilium
* auricular surface of the sacrum
* fibrous part= Tuberosities for fibrous part of the joint
Sacroiliac Ligaments – Anterior
Anterior sacroiliac ligament
* Iliolumbar ligament
* Interosseus Sacroiliac ligament
Sacroiliac Ligaments – Posterior
- Posterior/dorsal sacroiliac ligament
- Long & short fibres
- Sacrotuberous ligament
- Sacrospinous ligament
Weight Transfer through the Pelvis
- Sacrum is suspended between innominate bones
- Weight pushes the sacrum inferiorly
- Sacrum becomes ‘wedged’ in
- Irregular joint surfaces interlock
- Ligaments come under tension
- Ligament attachments mean the ilia are pulled towards the sacrum
- The sacroiliac joint self-locks
Sacroiliac Joint Movements
- Due to forces
- Not due to muscles
- Movements
- Small amounts of
- Gliding
- Rotation
- Nutation
- Anterior rotation of superior sacrum
- Counter-nutation
- Anterior rotation of inferior sacrum
- Nutation is resisted by
- Sacrotuberous ligament
- Sacrospinous ligament
form closure
describes the stability of the joint/from pelvic anatomy design (passive structures)
- Joint surface configuration - ridged, interlocking surfaces
- Joint surface alignment relative to gravity and bodyweight - “keystone-like” shape
- Tension in the restraining ligaments associated with normal alignment of the segments
force closures
s the term used to describe the other forces acting across pelvic joints to create stability (active structures including fascia)
- Force (active structures):
- Refers to the interaction of multiple muscle groups
- Act across the joint to enhance compression on the joint surfaces
- This assists in joint stability
- Is the so-called active myofascial oblique sling system
when does nutation occur
- when the sacrum absorbs shock
- The sacrum moves down, anteriorly (superior sacrum)
- As the superior sacrum moves anteriorly and inferiorly, the coccyx moves posteriorly relative to the ilium
- This motion is opposed by the wedge shape of the sacrum, the ridges and depression of the articular surfaces
- The integrity of the posterior, interosseous, sacrospinous, and sacrotuberous ligaments that are also supported by muscles that insert into the ligaments
